alt Hacker NewsThe benefits are twofold: physical colocation and bandwidth.
Thunderbolt 5 offers 80Gbps of bidirectional bandwidth. PCIe 5.0 16x offers 1024Gbps of bidirectional bandwidth. This matters.
TB5 cables can only get so long whereas fiber can go much farther more easily. This means that in a data center type environment, you could virtualize your GPUs and attach them as necessary, putting them in a separate bank (probably on the same rack).
Replies
mikepurvis • yesterday at 8:05 PM
"same rack" should still be fine for 1m passive TB5 cable though, right?
consp • yesterday at 8:06 PM
> 1024Gbps
Good luck getting a 1Tbit tranceiver. Anydirectional. Also it's 512Gbitish per direction.
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Active optical (yes!) Thunderbolt cables can be much longer. After all, optical fiber was the original medium for Thunderbolt, back when it was still called Light Peak.
I couldn’t find any optical TB5 cables, but here’s a 4.5m TB4 one: https://www.owc.com/blog/the-new-superlong-40gb-s-owc-active...
And if TB3 is enough, Corning makes them in lengths up to 50m: https://www.corning.com/microsites/coc/oem/documents/ocbc/OE...
As for bandwidth, the medium transition seems to actually limit the author’s capabilities by losing some of the more advanced link-training features that are necessary for the highest-bandwidth PCIe 3 connections, never mind PCIe 5.